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  • Selective thermal emitters based on photonic crystals  Open access

     Hernández García, David
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

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    Un dels límits fonamentals que afecta l'eficiència de conversió en cèl·lules fotovoltaiques és la distribució espectral de la radiació solar. D'una banda, només els fotons amb energia superior al gap del semiconductor poden convertir-se en electricitat a la cèl·lula. Els fotons de baixa energia no generen parells electró-forat. D'altra banda, l'excés d'energia dels portadors generats per fotons de molt alta energia es perd ràpidament per termalització en el propi dispositiu. Aquests fotons d'alta energia no generen una major energia elèctrica, pel que l'excés d'energia òptica es perd.Per superar aquesta limitació, la investigació s'ha centrat majoritàriament en millorar la conversió directa de fotons d'alta i baixa energia a través de, per exemple, l'ús d'up- i down-converters. Una alternativa menys estudiada consisteix en adaptar la radiació solar al dispositiu com a pas previ a la conversió. Aquesta adaptació es realitza mitjançant l'ús d'emissors selectius òpticament adaptats al semiconductor. Un emissor selectiu és un material amb una emissió tèrmica que ocupa una banda espectral estreta, en comptes d'emetre en tot l'espectre freqüencial. Aquests emissors són una alternativa eficient per obtenir grans conversions, treballant a temperatures al voltant dels 1500 K, donat que un material calentat pel Sol, o una altra font d'energia, pot reemetre llum amb una distribució espectral molt més adequada al dispositiu fotovoltaic. Aquest mode d'operació es coneix com a conversió d'energia termofotovoltaica.A la natura existeixen materials capaços de comportar-se com emissors selectius. Els òxids de terres rares representen un interesant camp d'investigació. Aquests òxids tenen una emissió tèrmica molt baixa en tot l'espectre excepte a certes freqüències. Aquestes freqüències d'emissió són úniques i selectives i provenen de ressonàncies a l'estructura cristal·lina del material. El desavantatge en la seva utilització radica en què la posició espectral d'aquests pico d'emissió, propis del material i la seva estructura, no pot ser controlada. A més, aquestes bandes d'emissió són relativament estretes, generant una baixa densitat de potència radiada.Per tant, existeix la necessitat de treballar amb materials amb una banda d'emissió selectiva que pugui ser dissenyada i controlada convenientment. La solució és l'ús de cristalls fotònics (materials artificials amb propietats òptiques que no existeixen en la natura). Encara que la seva fabricació presenta molts reptes, aquests cristalls artificials permeten el control de l'emissió espontània, suprimint-la o potenciant-la a la banda freqüencial d'interès.Existeixen varies interaccions que permeten aquest control: l'efecte de banda prohibida, la interacció per plasmons o fonons, o l'efecte de microcavitat. Tots permeten modificar l'espectre d'emissió tèrmica d'un material.La present tesis doctoral està dedicada a l'estudi de les propietats d'emissió tèrmica, i estabilitat tèrmica, d'emissors selectius basats en cristalls fotònics. S'han analitzat varies estructures: cristalls fotònics basats en silici macroporós, quasi-cristalls fotònics i microcavitats metàl·liques. També, en col·laboració amb altres grups d'investigació, s'han analitzat les propietats tèrmiques de cristalls col·loïdals.En el present treball, es mostra que els cristalls i quasi-cristalls basats en silici macroporós poden inhibir eficientment la radiació tèrmica de manera controlable, sent a més estables a alta temperatura fins 1500 K. Respecte els cristalls metàl·lics, l'estudi realitzat mostra la seva alta selectivitat espectral, encara que aquests emissors han de treballar a temperatures inferiors a 1100 K per garantir la seva estabilitat estructural i òptica.

    Un dels límits fonamentals que afecta l'eficiència de conversió en cèl·lules fotovoltaiques és la distribució espectral de la radiació solar. D'una banda, només els fotons amb energia superior al gap del semiconductor poden convertir-se en electricitat a la cèl·lula. Els fotons de baixa energia no generen parells electró-forat. D'altra banda, l'excés d'energia dels portadors generats per fotons de molt alta energia es perd ràpidament per termalització en el propi dispositiu. Aquests fotons d'alta energia no generen una major energia elèctrica, pel que l'excés d'energia òptica es perd. Per superar aquesta limitació, la investigació s'ha centrat majoritàriament en millorar la conversió directa de fotons d'alta i baixa energia a través de, per exemple, l'ús d'up- i down-converters. Una alternativa menys estudiada consisteix en adaptar la radiació solar al dispositiu com a pas previ a la conversió. Aquesta adaptació es realitza mitjançant l'ús d'emissors selectius òpticament adaptats al semiconductor. Un emissor selectiu és un material amb una emissió tèrmica que ocupa una banda espectral estreta, en comptes d'emetre en tot l'espectre freqüencial. Aquests emissors són una alternativa eficient per obtenir grans conversions, treballant a temperatures al voltant dels 1500 K, donat que un material calentat pel Sol, o una altra font d'energia, pot reemetre llum amb una distribució espectral molt més adequada al dispositiu fotovoltaic. Aquest mode d'operació es coneix com a conversió d'energia termofotovoltaica. A la natura existeixen materials capaços de comportar-se com emissors selectius. Els òxids de terres rares representen un interesant camp d'investigació. Aquests òxids tenen una emissió tèrmica molt baixa en tot l'espectre excepte a certes freqüències. Aquestes freqüències d'emissió són úniques i selectives i provenen de ressonàncies a l'estructura cristal·lina del material. El desavantatge en la seva utilització radica en què la posició espectral d'aquests pico d'emissió, propis del material i la seva estructura, no pot ser controlada. A més, aquestes bandes d'emissió són relativament estretes, generant una baixa densitat de potència radiada. Per tant, existeix la necessitat de treballar amb materials amb una banda d'emissió selectiva que pugui ser dissenyada i controlada convenientment. La solució és l'ús de cristalls fotònics (materials artificials amb propietats òptiques que no existeixen en la natura). Encara que la seva fabricació presenta molts reptes, aquests cristalls artificials permeten el control de l'emissió espontània, suprimint-la o potenciant-la a la banda freqüencial d'interès. Existeixen varies interaccions que permeten aquest control: l'efecte de banda prohibida, la interacció per plasmons o fonons, o l'efecte de microcavitat. Tots permeten modificar l'espectre d'emissió tèrmica d'un material. La present tesis doctoral està dedicada a l'estudi de les propietats d'emissió tèrmica, i estabilitat tèrmica, d'emissors selectius basats en cristalls fotònics. S'han analitzat varies estructures: cristalls fotònics basats en silici macroporós, quasi-cristalls fotònics i microcavitats metàl·liques. També, en col·laboració amb altres grups d'investigació, s'han analitzat les propietats tèrmiques de cristalls col·loïdals. En el present treball, es mostra que els cristalls i quasi-cristalls basats en silici macroporós poden inhibir eficientment la radiació tèrmica de manera controlable, sent a més estables a alta temperatura fins 1500 K. Respecte els cristalls metàl·lics, l'estudi realitzat mostra la seva alta selectivitat espectral, encara que aquests emissors han de treballar a temperatures inferiors a 1100 K per garantir la seva estabilitat estructural i òptica.

    One of the fundamental limits of conversion efficiency in photovoltaic cells is the broadband distribution of solar spectrum. On one hand, only photons with energy higher than the semiconductor's bandgap can be converted in the device, on the other hand, carriers generated by high energy photons rapidly loose their excess of energy by thermalization with the lattice. To overcome this limitation, and span the useful convertible region of solar spectrum, many approaches have focused on improving the direct photon to electron conversion by the development of up- and down-converters. A less studied alternative, however, is the use of spectrally narrow distributed emitters, optically matched with the gap energy of the photovoltaic cell, instead of direct sunlight. Indeed, a material heated by the sun, or another energy source as methane or hydrogen, can re-emit light with suitable spectral distribution and significant higher power density, improving conversion efficiencies in solar cells. This way of operation is known as thermophotovoltaic energy conversion. Several materials have been considered to be used as emitters in thermophotovoltaic systems. Silicon carbide is a common one, thanks to its high stability at temperatures up to >2000 K. However, its broadband spectral emission limits the conversion efficiency in the photovoltaic device and forces to work at elevated temperatures. Selective emitters, which stand for materials whose thermal emission occupies a narrow spectral region, are a promising alternative to reach elevated conversion efficiencies at lower temperatures. Natural selective emitters as rare earths have attracted considerable research interest as they present unique emission peaks with the highest emittance level. This approach, however, presents some drawbacks, the spectral position where strong emission appears is not controllable, and the width of the emission band is relatively narrow, leading to a low power density emitted by the source. An advantageous way to engineer the selective emission of a thermal source and control the spectral position and bandwidth of strong emission, is by making use of photonic crystals (articial materials engineered to show optical properties that may not be found in nature). The spectral control of the spontaneous emission in such materials is a unique feature of photonic crystals, although their fabrication, mainly in three-dimensions, is still challenging. Several interactions between photonic crystals and radiation have been reported: the photonic bandgap effect, surface plasmon polaritons, phonon polaritons, or the microcavity effect, to give some examples. All these approaches allow engineering the thermal emission of materials to match the energy band of the photovoltaic cell and benefit the optical to electrical conversion efficiency, although some limitations arise when utilized in high temperature thermophotovoltaic systems which will be analyzed during the realization of this thesis. This thesis is therefore devoted to the study of the thermal emission properties and thermal stability of photonic crystal based selective emitters. Various structures have been analyzed: macroporous silicon crystals, photonic quasi-crystals and metallic microcavities. A study in self-assembled colloidal crystals was also started and the preliminary results are presented in the appendix of the document. Here, it is demonstrated that macroporous silicon crystals and quasi-crystals can inhibit thermal radiation in a controllable manner with thermal stability up to 1500 K. The great selective emission properties of metallic microcavities is also demonstrated, although the working temperature of such structures is limited below 1100 K to prevent degradation of the metallic layer.

  • Grup de Recerca en Micro i Nanotecnologies (MNT)

     Alcubilla Gonzalez, Ramon; Puigdollers Gonzalez, Joaquin; Voz Sanchez, Cristobal; Rodriguez Martinez, Angel; Martin Garcia, Isidro; Bardes Llorensi, Daniel; Bermejo Broto, Alexandra; Calderer Cardona, Josep; Dominguez Pumar, Manuel M.; Prat Viñas, Luis; Garcies Salva, Pau; Jimenez Serres, Vicente; Lopez Gonzalez, Juan Miguel; Orpella Garcia, Alberto; Ortega Villasclaras, Pablo Rafael; Pons Nin, Joan; Silvestre Berges, Santiago; Garin Escriva, Moises; Colina Brito, Monica Alejandra; Morales Vilches, Ana Belen; Coll Valenti, Arnau; Lopez Rodriguez, Gema; Castañer Muñoz, Luis Maria
    Competitive project

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  • Single-Step multiple-layers wafer slicing from macroporous silicon

     Garin Escriva, Moises; Hernández García, David; Todorov Trifonov, Trifon; Cardador, D.; Alcubilla Gonzalez, Ramon
    European Photovoltaic Solar Energy Conference and Exhibition
    p. 933-936
    DOI: 10.4229/28thEUPVSEC2013-2CO.2.5
    Presentation's date: 2013-10-01
    Presentation of work at congresses

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    There is a rising interest, from both photovoltaics and microelectronics industry, in wafer thickness reduction. During the last decade, it has been steadily reduced from 350 µm to 180 µm, but benefits are foreseen for thicknesses well below these values. The current sawing technology, however, suffers from large kerf losses and further reductions are increasingly difficult. Several technologies have emerged aiming to produce thin Si foils from a wafer, such as layer transfer, induced cleaving, or pore reorganization. These methods produce a single layer by step. In this work we report on a method able to produce many crystalline layers from a single silicon wafer and in a single fabrication step.

  • Procedimiento para la obtención de múltiples capas de silicio cristalino a partir de una oblea de silicio

     Alcubilla Gonzalez, Ramon; Todorov Trifonov, Trifon; Hernández García, David; Garin Escriva, Moises
    Date of request: 2012-06-13
    Invention patent

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    Procedimiento para la obtención de múltiples capas de silicio cristalino a partir de una oblea de silicio.

    Se divulga un método y sistema para la fabricación de multicapas de silicio cristalino a partir de una oblea de silicio por el cual se puede controlar el grosor de las distintas capas para que varíe desde la escala de cientos de nanómetros a la escala de decenas de micrómetros. El método de fabricación comprende etapas de litografía, de ataques electroquímicos, y recristalización de la oblea al mismo tiempo que se controlan los parámetros de reacción.

  • Optical properties of Al2O3 and TiO2 coated 3D macroporous silicon photonic crystals

     Todorov Trifonov, Trifon; Hernández García, David; Garin Escriva, Moises; Vega Bru, Didac; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Spanish Conference on Electron Devices
    p. 47-48
    Presentation's date: 2011-02-10
    Presentation of work at congresses

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    Tuning the emissivity of 3D macroporous silicon in the mid-infrared  Open access

     Hernández García, David; Vega Bru, Didac; Garin Escriva, Moises; Todorov Trifonov, Trifon; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Encuentro Franco-Español de Química y Física del Estado Sólido
    p. 33-34
    Presentation's date: 2010-03-17
    Presentation of work at congresses

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    Tailoring the thermal emission of a particular material by using periodic micro-structures has attracted great interest for its potential applications in heating and lighting systems or thermophotovoltaics. […] Metallic and dielectric gratings, can be designed to introduce sharp emissions peaks which can be controlled with the grating parameters. 3D photonic band gap materials are particularly flexible in managing and confining light and, therefore, they are excellent candidates for controlling thermal radiation. Macroporous silicon, consisting of periodic arrays of etched pores in hydrofluoric acid solution, is a versatile material that provides large-area, high-quality and thermally-stable microstructures. It features full three-dimensionality, well controlled pore distribution and growth, and scalable dimensions in a range from 0.5 μm up to 100 μm. Silicon 3D structures operate at infrared wavelengths, efficiently reducing the emissivity inside the PBG regions. We present several Si microstructures and their emissivity/reflectivity responses measured by FT-IR spectrometry.

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    Template fabrication of 3D metallic microstructures by electrochemical etching and electroplanting  Open access

     Hernández García, David; Todorov Trifonov, Trifon; Lange, Diego; Garin Escriva, Moises; Garcia Molina, Miguel; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Encuentro Franco-Español de Química y Física del Estado Sólido
    p. 1-2
    Presentation of work at congresses

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    In this work, we show that macroporous silicon consisting of periodic arrays of etched pores is a feasible alternative for synthesis of 2D and 3d metallic microstructures due to its flexibility in the definition of complex geometries bulk. In addition macroporous silicon features full three-dimensionality, well controlled pore distribution and growth, and scalable dimensions (0.5-100 μm). We present here the fabrication of 3D Ni micro-structures by electroplating of macroporous silicon templates. The given approach can be applied for depositions of different metals and in more complicated template-structures.

  • Engineering the thermal emission of macroporous silicon

     Garin Escriva, Moises
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

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  • 3D metallo-dielectric structures combining electrochemical and electroplating techniques

     Hernández García, David; Lange, Diego; Todorov Trifonov, Trifon; Garin Escriva, Moises; Garcia Molina, Francisco Miguel; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Micro Nano Engineering
    p. 273-281
    DOI: 10.1016/j.mee.2009.11.108
    Presentation's date: 2009-09
    Presentation of work at congresses

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  • Effects of periodicity and shape on the optical and thermal emission properties of 3D macroporous silicon

     Rodriguez Martinez, Angel; Todorov Trifonov, Trifon; Garin Escriva, Moises; Alcubilla Gonzalez, Ramon
    International Conference on Porous Semiconductors Science and Technology PSST
    p. 238-239
    Presentation's date: 2008-03
    Presentation of work at congresses

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  • c-Si surface passivation for photovoltaic applications by means of antireflective amorphous silicon carbide layers

     Ferre Tomas, Rafel; Martin Garcia, Isidro; Ortega Villasclaras, Pablo Rafael; Vetter, Michael; Garin Escriva, Moises; Alcubilla Gonzalez, Ramon
    Spanish Conference on Electron Devices
    p. 238-241
    Presentation of work at congresses

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  • Effect of Bias Light on Effective Lifetime Measurements of Samples Dominated by the Depletion Region Modulation Effect

     Martin Garcia, Isidro; Bermejo Broto, Alexandra; Garin Escriva, Moises; Alcubilla Gonzalez, Ramon
    22nd European Photovoltaic Solar Energy Conference
    p. 1378-1381
    Presentation of work at congresses

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  • Optical properties of 3D macroporous silicon structures

     Garin Escriva, Moises; Todorov Trifonov, Trifon; Rodriguez Martinez, Angel; Marsal, L F; Alcubilla Gonzalez, Ramon
    E-MRS 2007 Spring Meeting
    Presentation of work at congresses

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  • Post-etching shaping of macroporous silicon

     Todorov Trifonov, Trifon; Garin Escriva, Moises; Ortega Villasclaras, Pablo Rafael; Marsal, L F; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    SPIE Europe MICROTECHNOLOGIES FOR THE NEW MILLENNIUM 2007
    p. 51
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  • Towards more complex shapes of macroporous silicon

     Todorov Trifonov, Trifon; Garin Escriva, Moises; Rodriguez Martinez, Angel; Marsal, L F; Pallarès Marzal, Josep; Alcubilla Gonzalez, Ramon
    Spanish Conference on Electron Devices
    p. 9-12
    Presentation of work at congresses

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  • TEC2005-02716/MIC Nuevas tecnologías de fabricación de células solares fotovoltaicas

     Alcubilla Gonzalez, Ramon; Puigdollers Gonzalez, Joaquin; Orpella Garcia, Alberto; Martin Garcia, Isidro; Garin Escriva, Moises
    Competitive project

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  • Comparison of the surface passivation quality of SiNx and SiCx films on p-type and n-type multicrystalline Silicon

     Vetter, Michael; Bermejo Broto, Alexandra; Martin Garcia, Isidro; Garin Escriva, Moises; Alcubilla Gonzalez, Ramon; Riepe, S; Rein, S; Warta, W
    20th European Photovoltaic Solar Energy Conference and Exhibition
    p. 1454-1457
    Presentation of work at congresses

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  • Analysis of Interface Recombination Parameters in c-Si Passivated with Dielectric Films

     Garin Escriva, Moises; Martin Garcia, Isidro; Vetter, Michael; Orpella Garcia, Alberto; Puigdollers Gonzalez, Joaquin; Voz Sanchez, Cristobal; Alcubilla Gonzalez, Ramon
    European Photovoltaic Solar Energy Conference
    p. 1
    Presentation of work at congresses

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  • Characterization of bifacial heterojunction Silicon solar cells obtained by Hot-Wire CVD

     Muñoz, D; Voz Sanchez, Cristobal; Fonrodona, M; Garin Escriva, Moises; Orpella Garcia, Alberto; Vetter, Michael; Puigdollers Gonzalez, Joaquin; Alcubilla Gonzalez, Ramon; Villar, F; Bertoeu, J; Andreu, Jordi
    Journal of non-crystalline solids
    Vol. 352, p. 1953-1957
    Date of publication: 2006-07
    Journal article

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  • Crystalline Silicon surface passivation by amorphous Silicon Carbide films

     Vetter, Michael; Martin Garcia, Isidro; Ferre Tomas, Rafel; Garin Escriva, Moises; Alcubilla Gonzalez, Ramon
    Solar energy materials and solar cells
    Vol. 91, num. 2-3, p. 174-179
    Date of publication: 2006-10
    Journal article

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  • Fixed charge density in dielectrics deposited on c-Si using space charge region dominated lifetime measurements

     Garin Escriva, Moises; Martin Garcia, Isidro; Bermejo Broto, Alexandra; Alcubilla Gonzalez, Ramon
    Journal of applied physics
    Vol. 101, num. 12, p. 1-7
    Date of publication: 2007-06
    Journal article

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  • Tuning the shape of macroporous silicon

     Todorov Trifonov, Trifon; Garin Escriva, Moises; Rodriguez Martinez, Angel; Marsal, L F; Alcubilla Gonzalez, Ramon
    Physica status solidi A. Applications and materials science (Print edition)
    Vol. 204, num. 10, p. 3237-3242
    Date of publication: 2007-10
    Journal article

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  • Infrared thermal emission in macroporous silicon three-dimensional photonic crystals

     Garin Escriva, Moises; Todorov Trifonov, Trifon; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Applied physics letters
    Vol. 91, num. 18, p. 1-3
    Date of publication: 2007-10
    Journal article

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  • Improving selective thermal emission properties of three-dimensional macroporous silicon through porosity tuning

     Garin Escriva, Moises; Todorov Trifonov, Trifon; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon; Marquier, R; Arnold, C; Greffet, Jj
    Applied physics letters
    Vol. 93, num. 8, p. 081913-081913-3
    DOI: 10.1063/1.2976144
    Date of publication: 2008-08
    Journal article

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  • Optical properties of 3D macroporous silicon structures

     Garin Escriva, Moises; Todorov Trifonov, Trifon; Rodriguez Martinez, Angel; Marsal, L F; Alcubilla Gonzalez, Ramon
    Materials science and engineering B. Solid state materials for advanced tech
    Vol. 149, num. 3, p. 275-280
    Date of publication: 2008-04
    Journal article

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  • Crystalline Silicon surface passivation with amorphous SiCx:H films deposited by Plasma- Enhanced Chemical Vapor Deposition

     Martin Garcia, Isidro; Vetter, Michael; Garin Escriva, Moises; Orpella Garcia, Alberto; Voz Sanchez, Cristobal; Puigdollers Gonzalez, Joaquin; Alcubilla Gonzalez, Ramon
    Journal of applied physics
    num. 98, p. 1-10
    Date of publication: 2005-12
    Journal article

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  • Characterization of a-Si:H/c-Si interfaces by effective-lifetime measurements

     Garin Escriva, Moises; Rau, U; Bredle, W; Martin Garcia, Isidro; Alcubilla Gonzalez, Ramon
    Journal of applied physics
    Vol. 9, num. 98, p. 1-9
    Date of publication: 2005-11
    Journal article

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    All-silicon spherical-Mie-resonator photodiode with spectral response in the infrared region  Open access

     Garin Escriva, Moises; Fenollosa Esteve, Roberto; Alcubilla Gonzalez, Ramon; Shi, Lei; Marsal Garvi, Luis Francisco; Meseguer Rico, Francisco Javier
    Nature communications
    Vol. 5, num. 3440, p. 1-6
    DOI: 10.1038/ncomms4440
    Date of publication: 2014-03-10
    Journal article

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    Silicon is the material of choice for visible light photodetection and solar cell fabrication. However, due to the intrinsic band gap properties of silicon, most infrared photons are energetically useless. Here, we show the first example of a photodiode developed on a micrometre scale sphere made of polycrystalline silicon whose photocurrent shows the Mie modes of a classical spherical resonator. The long dwell time of resonating photons enhances the photocurrent response, extending it into the infrared region well beyond the absorption edge of bulk silicon. It opens the door for developing solar cells and photodetectors that may harvest infrared light more efficiently than silicon photovoltaic devices that are so far developed.

  • Silicon colloids: A new enabling nanomaterial

     Meseguer Rico, Francisco Javier; Fenollosa Esteve, Roberto; Rodriguez, Isabelle; Xifré Pérez, Elisabet; Ramiro Manzano, Fernando; Garin Escriva, Moises; Tymczenko, Michael
    Journal of applied physics
    Vol. 109, p. 102424-1-102424-6
    DOI: 10.1063/1.3581880
    Date of publication: 2011-05-31
    Journal article

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    We have recently developed a new type of silicon structure that we refer to as a silicon colloid. This new material consists of almost perfectly spherical silicon micro- and nanoparticles with a very smooth surface. They are able to trap light very efficiently in a large-span frequency range covering the visible to the far infrared regions. Silicon colloids can be thought of as a completely new material for scientific and technological purposes, with manifold applications covering electronics, photonics, cosmetics, or paints, among others. Here, we report on the synthesis of polycrystalline, amorphous, and porous silicon colloids, as well as their optical properties, some applications concerning light filters, and photonic bonding.

  • Coherent thermal infrared emission by two-dimensional silicon carbide gratings

     Arnold, Christophe; Marquier, François; Garin Escriva, Moises; Pardo, Fabrice; Collin, Stéphane; Bardou, Nathalie; Pelouard, Jean-Luc; Greffet, Jean-Jacques
    Physical review B: condensed matter and materials physics
    Vol. 86, p. 035316-1-035316-6
    DOI: 10.1103/PhysRevB.86.035316
    Date of publication: 2012-07-17
    Journal article

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    The thermal emission of cross-slit silicon carbide grating is studied in the Restrahlen region over all emission angles. We show experimentally that the thermal excitation of surface-phonon polaritons on the surface of 2D grating allows us to get a high emissivity in both polarizations, which is collimated in p polarization for a specific wavelength determined by the periodicity of the grating. We also show numerically that 2D gratings optimized to efficiently out-couple thermally excited surface-phonon polaritons of the flat part of the dispersion relation can have a high efficiency for all emission directions for both polarizations.

  • Porous silicon microcavities based photonic barcodes

     Ramiro Manzano, Fernando; Fenollosa Esteve, Roberto; Xifré Pérez, Elisabet; Garin Escriva, Moises; Meseguer Rico, Francisco Javier
    Advanced materials
    Vol. 23, num. 27, p. 3022-3025
    DOI: 10.1002/adma.201100986
    Date of publication: 2011-07-19
    Journal article

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    A new type of porous silicon based microcavity has been developed. The intrinsic photoluminiscence emission is strongly coupled to the whispering gallery modes of the microcavity resulting in a unique photonic fingerprint of each particle. It may be envisaged as a photonic bar code like luminescent profile associated to each single particle.

  • Porous silicon microcavities: synthesis, characterization, and application to photonic barcode devices

     Ramiro Manzano, Fernando; Fenollosa Esteve, Roberto; Xifré Pérez, Elisabet; Garin Escriva, Moises; Meseguer Rico, Francisco Javier
    Nanoscale research letters
    Vol. 7, num. 497, p. 1-6
    DOI: 10.1186/1556-276X-7-497
    Date of publication: 2012-09-03
    Journal article

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    We have recently developed a new type of porous silicon we name as porous silicon colloids. They consist of almost perfect spherical silicon nanoparticles with a very smooth surface, able to scatter (and also trap) light very efficiently in a large-span frequency range. Porous silicon colloids have unique properties because of the following: (a) they behave as optical microcavities with a high refractive index, and (b) the intrinsic photoluminescence (PL) emission is coupled to the optical modes of the microcavity resulting in a unique luminescence spectrum profile. The PL spectrum constitutes an optical fingerprint identifying each particle, with application for biosensing. In this paper, we review the synthesis of silicon colloids for developing porous nanoparticles. We also report on the optical properties with special emphasis in the PL emission of porous silicon microcavities. Finally, we present the photonic barcode concept.

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    Silicon microcavity-based photovoltaic cells for IR harvesting  Open access

     Garin Escriva, Moises; Fenollosa Esteve, Roberto; Alcubilla Gonzalez, Ramon; Shi, Lei; Marsal Garví, Lluis; Meseguer Rico, Francisco Javier
    SPIE Newsroom
    DOI: 10.1117/2.1201405.005483
    Date of publication: 2014-05-22
    Journal article

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    Photovoltaic cells on silicon spherical microcavities trap IR light, increasing the probability of photon absorption and enhancing the efficiency of solar energy devices.

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    ¿Silicon millefeuille¿ : From a silicon wafer to multiple thin crystalline films in a single step  Open access

     Hernández García, David; Todorov Trifonov, Trifon; Garin Escriva, Moises; Alcubilla Gonzalez, Ramon
    Applied physics letters
    Vol. 102, num. 17, p. 1-4
    DOI: 10.1063/1.4803009
    Date of publication: 2013-04-29
    Journal article

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    During the last years, many techniques have been developed to obtain thin crystalline films from commercial silicon ingots. Large market applications are foreseen in the photovoltaic field, where important cost reductions are predicted, and also in advanced microelectronics technologies as three-dimensional integration, system on foil, or silicon interposers [Dross et al., Prog. Photovoltaics 20, 770-784 (2012); R.Brendel, Thin Film Crystalline Silicon Solar Cells (Wiley-VCH, Weinheim, Germany 2003); J. N. Burghartz, Ultra-Thin Chip Technology and Applications (Springer ScienceþBusiness Media, NY, USA, 2010)]. Existing methods produce “one at a time” silicon layers, once one thin film is obtained, the complete process is repeated to obtain the next layer. Here, we describe a technology that, from a single crystalline silicon wafer, produces a large number of crystalline films with controlled thickness in a single technological step.

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    Emissive properties of SiO2 thin films through photonic windows  Open access

     Hernández García, David; Garin Escriva, Moises; Todorov Trifonov, Trifon; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Applied physics letters
    Vol. 100, num. 9, p. 091901-1-091901-3
    Date of publication: 2012-02
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  • 3D metallo-dielectric structures combining electrochemical and electroplating techniques

     Hernández, D.; Lange, Diego; Todorov Trifonov, Trifon; Garin Escriva, Moises; Garcia Molina, Francisco Miguel; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Microelectronic engineering
    Vol. 87, num. 5-8, p. 1458-1462
    DOI: 10.1016/j.mee.2009.11.108
    Date of publication: 2010-06
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    Three-dimensional (3D) periodic nickel micro-structures with a periodicity of 4 μm and high number of structural periods were fabricated by electrodeposition. Macroporous silicon, consisting of periodic arrays of sine-wave modulated pores, was used as a deposition template. It was prepared by electrochemical etching of silicon and subsequent pore widening by multiple oxidation/oxide-removal steps. The pore widening allows to open windows between adjacent pores obtaining a 3D network of interconnected voids embedded in silicon. This structure is then void-free filled with nickel in the electroplating process. The combination of electrochemical etching and electroplating techniques opens a route for the fabrication of large-scale 3D-periodic metallic micro-structures.

  • Thermal emission of macroporous silicon chirped photonic crystals

     Garin Escriva, Moises; Todorov Trifonov, Trifon; Hernández García, David; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon
    Optics letters
    Vol. 35, num. 20, p. 3348-3350
    DOI: 10.1364/OL.35.003348
    Date of publication: 2010-09-15
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